建筑与小区绿地的径流削减效果影响因子及径流系数研究

Urban green space has the hydrological regulation function of interception, infiltration and slow release of rainwater runoff. However, due to complex factors of building and sub-district, the influencing factors and values of runoff coefficient of its green space need to be further studied. This research from the interdisciplinary perspective of landscape architecture, ecology, hydrology and hydraulics, taking green space of building and sub-district as object, studies the factors affecting the reduction of rainwater runoff and its mechanism, and the calculation method of the runoff coefficient of green space. Taking Beijing city as study area, the quantitative relationship between vegetation factor and runoff volume and flow reduction effect is analyzed through i-Tree Hydro model and Leaf Area Index method. The soil and terrain factors are studied by micro topography and artificial fill experiment under artificial rainfall conditions. Based on measuring runoff flow of sample area and mathematical statistics analysis, the relationship between multiple factors and volume runoff coefficient and flow runoff coefficient is established, and a prediction mathematical model is built to determine the range of runoff coefficient under different rainfall, vegetation composition, topography and soil conditions. The Storm Water Management Model (SWMM) model is used to analyze and evaluate the measures and combinations used in green space for hydrological regulation, and select the optimal model. This project can be used as a reference for the scientific evaluation of the effect of green space stormwater control and utilization, and the optimization design of rainwater system in building and sub-district.

城市绿地具有截留、促渗、缓释雨水径流的水文调节功能，但建筑小区因受复杂因素影响，其绿地的径流系数的影响因素和取值依据有待深入研究。本课题拟从园林、生态、水文水力的交叉学科视角，以建筑与小区绿地为对象，对影响雨水径流削减的因子及其作用机理，和绿地径流系数的计算方法展开研究。以北京市为研究区域，通过i-Tree Hydro模型、叶面积指数测定相结合的方法对植被因子与径流总量、流量削减效果的量化关系进行分析，通过人工降雨条件下的微地形和人工填土实验对土壤和地形因子展开研究；结合样地径流流量实测、数理统计分析建立多因子与雨量径流系数、流量径流系数的对应关系，构建预测数学模型，确定不同降雨、植被构成、地形、土壤条件下的径流系数取值范围；通过雨洪管理模型(SWMM)对提升绿地水文调节效益的措施及组合展开评估，筛选优选模式。本课题可为科学评估绿地雨洪控制利用效果、建筑与小区雨水系统优化设设计提供参考。

城市建筑与小区绿地产流过程受人工干扰程度大、影响因素复杂，本项目对建筑与小区绿地径流系数的影响因素和径流系数计算预测方法进行系统研究，具有较为重要的学术价值和现实意义。.本项目研究了在不同降雨情景下，绿地内植被、土壤、微地形等诸多因素对径流削减效果的影响，对这些因素和径流总量、峰值流量削减效果的量化关系进行剖析，揭示影响绿地径流系数取值的因素，提出典型情景下雨量、流量径流系数取值表，和强化绿地雨水径流总量和流量控制的优化途径。通过浸水实验、实地测量等方法，对北京城区21种典型植物的叶片吸水量、冠层截留量、冠层截留体积、植物群落场降雨截留率与多年平均降雨截留率进行计算与分析。结果表明：植物吸水量与浸水时间呈对数函数关系，常绿针叶植物冠层截留量明显高于落叶阔叶植物，植物冠层截留体积与冠层覆盖面积、植物冠层截留量成正相关关系，植物群落截留能力在中小降雨事件中较明显。通过实测、i-Tree Eco 模型模拟和航片分析评估了典型场地植被冠层的雨水截留和径流削减效益，推导了计算径流削减量的校准方法，并评估计算北京老城区植被冠层整体截留能力。通过试验研究与模型模拟对降雨重现期、降雨间隔、降雨峰值位置，植被种类，土壤厚度、土壤类型，坡度、平整度等因素做了研究。结果表明，土壤厚度越大，土壤达到饱和含水率所需入渗量越多径流量越小；且绿地产流量随坡度的增大而增加到某值后，会趋于稳定。同时，对研究条件下绿地径流系数的计算结果显示，绿地径流系数取值范围在0.02-0.52之间，其值随降雨重现期、雨峰位置、坡度、土壤厚度等单因素变量以及两两因素共同作用影响极大。.项目成果可为科学评估绿地雨水调蓄能力提供方法论，为海绵城市建设中城市绿地的优化设计提供参考。